Many people ask if it is possible to use Public Folders for data storage in regards to the redesigned Outlook Synchronization in releases after Dynamics NAV 4.0 taking into account that there are no conditions or filters set for the contacts entities. The answer is simple: yes, you can! There is one big pitfall. In scenarios where there are thousands of contacts to be synchronized, Exchange Server tend to think that this is not OK. There are some KB published on that topic:
http://support.microsoft.com/kb/830836
http://support.microsoft.com/kb/830829/

There are some more KB articles in regards to event ID 9646, but the two KB articles are more then enough in regards to the blog posting.

The question I usually ask partners and customer is why they want all the Dynamic related contacts to be synchronized to each and every salesperson? Can you imagine how large these mailbox will become and what that means for the underlying network in Cached Exchange Mode and in non Cached Exchange mode. The answer is in most cases, we did not assign our contacts to a specific salesperson. If those partners or customers try to synchronize the whole Dynamics NAV contacts database to Outlook, then nothing synchronizes! Sometimes partners and customers answers that table 13 is filled with regional codes in stead of real salespersoncodes, like EU1 (Northern European Countries), EU2 (Southern European Countries), etc.  

In this scenario, one may want to create three Public Folders for the three Contact entities without any condition and configure the Outlook Addin with the three Public Folders. In this scenario, one would still need a dedicated user account plus mailbox so that the Outlook Addin can be configured. Very easy, just create a mailbox enabled user on the Active Directory computer, configure that user in the Login table of Dynamics NAV with the necessary Roles, then configure the new user with at least the two Contact entities (Company contacts and Person contacts), registry that in the change log and you are done.

In the scenario of separating Scandinavian contacts from Italian contacts and so on, one could create two mailbox enabled users and one could configure those two users with the two contacts entities with a condition defined for each part of Europe. To summarize, this scenario would end up with two user account that are only being used for the Outlook Synchronization and at least four Public Folders.

Always remember that Tasks and Appointment must be somehow linked to a "salesperson". This is quite logical, because there must be a meeting Organizer and an Owner of the Tasks.